Conditioning of gaseous discharge display/memory device

ABSTRACT

There is disclosed a method for conditioning a multiple gaseous discharge display/memory device having an electrical memory and capable of producing a visual display, the device being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric material charge storage members which are respectively backed by a series of parallellike conductor (electrode) members, the conductor members behind each dielectric material member being transversely oriented with respect to the conductor members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit. The conditioning of the device comprises the combined use of a pilot unit and a pre-address voltage signal so as to supply free electrons to each discrete volume or unit in order that a discharge can be initiated when such conditioned unit is addressed.

United States Patent 1191 Nolan CONDITIONING OF GASEOUS DISCHARGE DISPLAY/MEMORY DEVICE [75] Inventor: James F. Nolan, Sylvania, Ohio [73] Assignee: Owens-Illinois, lnc., Toledo, Ohio [22] Filed: Jan. 4, 1971 [21] Appl. No.: 103,848

[52] US. Cl. 315/169 R, 313/188, 315/169 TV [51 1m. c1 ..H05b 37/00, H05b 39/00, H05b 41/09 [58] Field of Search 313/188; 315/169 TV, 169, 315/169 R [56] References Cited UNITED STATES PATENTS 3,559,190 1/1971 Bitzer et a1. 313/201 X 3,096,516 7/1963 Pendleton et a1. 315/169 TV 3,614,526 10/1971 Janning 313/188 3,499,167 3/1970 Baker et a1.... 315/169 TV 3,336,499 8/1967 O'Meara 313/188 X Primary Examiner-James W. Lawrence Assistant ExaminerSaxfield Chatmon, Jr. Attorney, Agent, or Firm-Donald Keith Wedding C-l C- 0-3 INTERFACE AND ADDRESSING ClRCUlT Apr. 9, 1974 ABSTRACT There is disclosed a method for conditioning a multiple gaseous discharge display/memory device having an electrical memory and capable of producing a visual display, the device being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric material charge storage members which are respectively backed by a series of parallel-like conductor (electrode) members, the conductor members behind each dielectric material member being transversely oriented with respect to the conductor members behind the opposing dielectric I material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit. The conditioning of the device comprises the combined use of a pilot unit and a pre-address voltage signal so as to supply free electrons to each discrete volume or unit in order that a discharge can be initiated when such conditioned unit is addressed.

9 Claims, 3 Drawing Figures THE INVENTION This invention relates to multiple gas discharge display/memory devices which have an electrical memory and which are capable of producing a visual display including the representation of data such as numerals, letters, television display, radar-displays, binary words, etc.

Multiple gas discharge display and/or memory devices of the type with which the present invention is concerned are characterized by an ionizable gaseous medium, usually a mixture of at least two gases at an appropriate gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor (electrode) members, the conductor members backing each dielectric member being transversely oriented to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit. In some prior art devices, the discharge units are additionally defined by surrounding or confining physical structure such as by cells or apertures in perforated glass plates and the like so as to be physically isolated relative to other units. In either case, with or without the confining physical structure, charges (electrons, ions) produced upon ionization of the gas of a selected discharge unit, when proper alternating operating potentials are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field opposing the electrical field which created them so as to terminate the discharge'for the remainder of the half cycle and aid in the initiation of a discharge'on a succeeding opposite half cycle of applied voltage, such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of any conductive current from the conductor members to the gaseous medium and also serve as collecting surfaces for ionized gaseous medium charges (electrons, ions) during the alternate half cycles of the AC. operating potentials, such charges collecting first on one elemental or discrete dielectric surface area and then on an opposing elemental or discrete dielectric surface area on alternate half cycles to constitute an electrical memory.

An example of a panel structure containing nonphysically isolated or open discharge units is disclosed in US. Pat. No. 3,499,167 issued to Theodore C. Baker, et al.

An example of a panel containing physically isolated units is disclosed in British Pat. specifications 1,161,832 and 1,161,833 and also in the article by D. L. Bitzer and H. G. Slottow entitled The Plasma Display Panel A Digitally Addressable Display With Inherent Memory, Proceeding of the Fall Joint Computer Conference, IEEE, SanFrancisco, Calif., Nov. 1966, pages 541 547.

In the operation of the panel, a continuous volume of ionizable gas is confined between a pair of dielectric surfaces backed by conductor arrays forming matrix elements. The cross conductor arrays may be orthogonally related (but any other configuration of conductor arrays may be used) to define a plurality of opposed pairs of charge storage areas on the surfaces of the dielectric bounding or confining the gas. Thus, for a conductor matrix having H rows and C columns the number of elemental discharge volumes will be the product H X C and the number of elemental or discrete areas will be twice the number of elemental discharge volumes.

The gas may be one which produces light (if visual display is an objective) and a copious supply of charges (ions and electrons) during discharge. In an open cell Baker, et a1 type panel, the gas pressure and the electric field are sufficient to laterally confine charges generated on discharge within elemental or discrete volumes of gas between opposed pairs of elemental or discrete dielectric areas within the perimeter of such areas, especially in a panel containing non-isolated units.

With respect to the memory function of agiven discharge panel, the allowable distance or spacing between the dielectric surfaces depends, among other things, on the frequency of the alternating current supply, the distance typically being greater for lower frequencies.

While the prior art does disclose gaseous discharge devices having externally positioned electrodes for initiating a gaseous discharge, sometimes called electrodeless discharges, such prior art devices utilize frequencies and spacings or discharge volumes and operating pressures such that although discharges are initiated in the gaseous medium, such discharges are ineffective or not utilized for charge generation and storage in the manner of the present invention.

The term memory margin isdefined herein as where V, is the'magnitude of the applied voltage at which a discharge is initiated in a discrete conditioned (as explained in the aforementioned Baker, et a1 patent) volume of gas defined by common areas of overlapping conductors and V is the magnitude of the minimum applied periodic-alternating voltage sufficient to sustain discharges once initiated. It will be understood that basic electrical'phenomena utilized in this invention is the generation of charges (ions and electrons) alternately storable at pairs of opposed or facing discrete points or areas on a pair of dielectric surfaces backed by conductors connected to a source of operating potential. Such stored charges result in an electrical field opposing the field produced by the applied potential that created them and hence operate to terminate ionization in the elemental gas volume between opposed or facing discrete points or areas of dielectric surface. The term sustain a discharge means producing a sequence of momentary discharges, one discharge for each half cycle of applied alternating sustaining voltage, once theelemental gas volume of the discharge unit has been fired, to maintain alternate storing of charges at pairs of opposed discrete areas on the dielectric surfaces. When a discharge unit is in such a state, it is said to be in the on state.

In the operation of a multiple gaseous discharge device, of the type described hereinbefore, it is necessary to condition the discrete elemental gas volume of each discharge unit by supplying at least one free electron thereto such thata gaseous discharge can be initiated when the unit is addressed with an operating voltage signal.

The prior art has disclosed and practiced various means for conditioning gaseous discharge units.

One such method comprises the use of external radiation, such as flooding part or all of the gaseous me dium of the panel with ultraviolet radiation. This external conditioning method has the obvious disadvantage that it is not always convenient or possible to provide external radiation to a panel, especially if the panel is in a remote position. Likewise, an external UV source required auxiliary equipment. Accordingly, the use of internal conditioning is generally preferred.

One internal conditioning means comprises using internal radiation, such as by the inclusion of a radioactive material and/or by the use of one or more so-called pilot discharge unit for the generation of photons.

As described in the Baker et al patent, the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas (discharge unit) to pass freely through the panel gas space so as to condition other and more remote elemental volumes of other discharge units.

However, such internal photon generation and electron conditioning of the panel gaseous medium becomes unreliable when a given discharge unit to be addressed is remote in distance (an inch or more) relative to the conditioning source, e.g. the pilot unit. Thus, a multiplicity of pilot units or cells may be required for the conditioning of a panel having a large geometric area.

Another means of panel conditioning comprises a socalled electronic process whereby an electronic conditioning signal or pulse is periodically applied to all of the panel discharge units, as disclosed for example in British Pat. specification 1,161,832, page 8, lines 56 to 76. However, electronic conditioning is selfconditioning and is only effective after a discharge unit has been previously conditioned; that is, electronic conditioning involves periodically discharging a unit and is therefore a way of maintaining the presence of free electrons. Accordingly, one cannot wait too long between the periodically applied conditioning pulses since there must be at least one free electron present in order to discharge and condition a unit.

In accordance with the practice of this invention,

there is provided an improved process of conditioning gaseous discharge panels, especially panels having a large geometric area.

More particularly, there is a process for rapidly and reliably conditioning a multiplicity of gaseous discharge units distributed over the relatively wide geometric area of a gas discharge device having at least one pilot unit in the on state, which process comprises selectively applying a preaddressing voltage signal to a series of connecting discharge units which are intermediate relative to at least one pilot unit and to each discharge unit to be addressed, said voltage being sufficient to propagate the gaseous medium conditioning from the pilot unit across the connecting intermediate units to each unit to be addressed.

The connecting, intermediate units do not necessarily have to be adjacent to each other or adjacent to the pilot unit or units to be addressed. Likewise, the units do not have to be arranged in a straight line. It is only essential that such intermediate units be geometrically arranged and positioned so that one unit photonically connects to another unit which photonically connects to another unit and so forth; that is, the intermediate units must photonically connect so as to pass the conditioning process from the pilot unit to the unit to be addressed. As a practical matter, the connecting units may be adjacent.

The features and advantages of the invention will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings:

FIGS. 1 and 2 illustrate pre-addressing or conditioning voltage signals for a gas discharge display/memory panel; and

FIG. 3 is a partially cut-away plan view of a gaseous discharge display/memory panel embodying the inventron.

Referring to FIG. 3, a typical gaseous discharge dis play/memory panel such as is disclosed in Baker, et al Pat. No. 3,499,167 is constituted by a pair of support plates 16 and 17, with a row conductor array 13 being on row plate 17 nd a column conductor array 14 being on column plate 16. These conductor arrays 13 and 14 in the operating or viewing area of the panel have a thin dielectric coating applied thereto and the plates are joined in spaced-apart relation by a spacer sealant member 15. An ionizable gaseous discharge medium which is typically a mixture of two gases such as neon and nitrogen at a selected pressure is confined in the thin chamber formed between the dielectric coatings.

The panel has an electrical memory constituted by the storage of charges produced by discharge on the surfaces of the dielectric in contact with the gas. Thus, the conductors are non-conductively coupled to the gaseous medium. As described above, the conductors in arrays 13 and 14 form a cross-conductor matrix wherein the discharge sites are arrayed in columns and rows, C-l to C-10 and R-1 to R-l0. The dielectric layers 20 prevent the passage of any conductive current from the matrix conductor member to the gaseous medium and also serve as the collecting surfaces for discharges in the ionizable gaseous medium during alternate half-cycles of the periodic operating potentials applied thereto.

An interface and addressing circuit or system 19 transmits a sustainer voltage, a firing voltage, and a conditioning signal'or pulse to each of the row and column conductors 13 and 14 as required.

Each of FIGS. 1 and 2 illustrates a pre-addressing or conditioning voltage signal Vc of a square or rectangular waveform having a time or pulse width t. The voltage signal is initiated from and returned to an initial state 0. In FIG. 1, there is further illustrated an adjusting voltage V for more conveniently returning the signal to the initial state 0.

Although the square or rectangular waveform of FIGS. 1 and 2 is preferred, any other suitable waveform or geometric shape may be used providing the time or pulse width t is sufficient to allow all of the intermediate connecting discharge units to fire. Although the same signal is applied simultaneously to all of the intermediate discharge units, each fires at a different, but sequential, time; that is, at a different point or position on the voltage signal curve. It is therefore essential that the overall time t (pulse width) be sufficient to allow each (and all) of these units to independently discharge and provide a free electron to the next unit and so on until the to-be-addressed unit has been conditioned.

In the specific practice hereof, the magnitude of the conditioning voltage must be sufficient to fire or discharge the discharge unit. However, if the voltage signal is applied to an operating discharge unit in the on state, the magnitude must not be great enough to interfere with or interrupt the operation of such unit; also the polarity of the signal Vc must be the same as the polarity of the preceding sustaining voltage half-cycle applied to the on unit.

As noted'hereinbefore, it has been found in the past that one method of conditioning a panel, i.e., providing initiating electrons to insure that an addressed site will turn on is to light one or more pilot cells in the panel. One problem with this method of conditioning is that turn on becomes unreliable when the addressed site is some distance away (an inch or so) from the pilot cell. Thus, it has not been practical to use only a relatively small number of pilot cells, e.g., one for large panels. This invention surmounts this difficulty by changing the method of addressing or writing somewhat, and making use of the fact that the conditioning process can be propagated across a panel at high speeds. More especially, this invention makes use of the fact that the conditioning process can be propagated across a panel at a speed of more than 2 inches/microsecond, thus allowing a pilot cell to condition a remote site reliably provided that the conditioning process is propagated across a number of intermediate sites.

One specific practice of this invention proposes to apply a voltage signal as shown' in FIGS. 1 and 2 to every cell of a panel immediately prior to addressing or writing at any site. Such a signal in FIGS. 1 or 2 causes two short duration discharges to occur at every site in the off state and does not cause any discharges at sites in the on state.

Referring again to FIG. 3, the border discharge units or cells, designated with an along row conductors R-1 and R-l0 and along column conductors C-1 and C-10 are normally maintained in the ON condition.

These border units, as described in Baker et al, will be designated hereinafter as pilot cells. Under normal addressing schemes, the pilot cells are too far away from remote addressed sites to insure reliable turn-on. This invention proposes to reliably turn on any site in the panel by applying a pre-address or pre-write signal, e.g. as shown in FIGS. 1 or 2, to all or a portion of the cell sites in the panel followed by the tum-on signal to the addressed site only. More specifically, for example, it may be desired to address the site R-4, C-6, designated with an X. Although the pilot cell R-l0, (1-6 is too far away from the addressed site R-7, 0-6 to reliably condition it, a pre-addressed signal applied between electrode C-6 and electrodes R-9, 8, 7, 6 and 5 can reliably condition the sites R-9, C-6; R-8, C-6; R-7, C-6; R-6; C-6; and R-5, C-6 nearer the pilot cell, causing them to discharge during the pre-write signal. Each of these cells in turn conditions its neighbor cell and the conditioning process is thus propagated along the panel to the addressed site R-l, C-6. Since the speed of propgation is approximately 2 inches per microsecond, the conditioning process may be propagated approximately 20 inches in a 10 microseconds pulse width or time duration for the pre-write signal shown in FIG. 1. If longer distances are required, the pulse width of the pre-write signal can be increased. It is, of course, possible to use more than one pilot cell and this may be desirable in some cases. However, it

6. pulse width pre-write signal, is sufficient to condition a 2 feet by 2 feet panel.

It should be noted that the pre-write signal does not have to be re-applied to the panel periodically to keep it in a conditioned state. For example, if a panel has every site ofi' for a long time (e.g., several hours), it would still require only one prewrite signal, immediately prior to the write signal, to insure reliable Writing at any site, provided only that at least one pilot cell is on when the pre-write signal is applied. Also, if writing is done at a rapid rate, it is not necessary to precede every write signal with a pre-write signal. Nothing is usually gained by having successive pre-write signals occur at time intervals less than about 500 microseconds.

I claim:

1. In a gaseous discharge display/memory device characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric charge storage members which are respectively backed by a series of electrode members, the electrode members behind each dielectric member being transversely oriented relative to the electrode members behind the opposing dielectric member so as to define a plurality of discrete discharge volumes in open photonic communication, each of which constitutes a discharge unit, and wherein an alternating current sustaining volage is maintained on all of said units and at least one discharge unit is in the ON state so as to serve as a pilot unit for the gaseous medium conditioning of other unit to be addressed, the improvement wherein a preaddressing voltage signal is applied between alternate half-cycles of said sustaining voltage to a series of intermediate units which connect at least one pilot unit to at least one unit to be addressed, said intermediate units being geometrically arranged such that they are photonically connected, said pre-addressing voltage signal being applied for sufficient time to discharge said series of intermediate units to propagate the conditioning of the gaseous medium from the pilot unit through the intermediate units to each unit to be addressed and having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units.

2. The invention of claim 1 wherein the preaddressing voltage is simultaneously applied to all of the discharge units of the panel.

3. The invention of claim 1 wherein the preaddressing voltage is of a square or rectangular waveform.

4. In a process for operating a gaseous discharge display/memory device, said device being characterized by an ionizable gaseous medium with a multiplicity of appears that one pilot cell, with a 20 microseconds voltage addressable gaseous discharge units in open photonic communication, an alternating current sustaining voltage being maintained on all of said units, the improvement which comprises conditioning the gaseous medium of at least one non-operating, nonaddressed unit by applying between alternate halfcycles of said sustaining voltage a pre-addressing firing voltage signal to one or'more intermediate units connecting the non-operating, non-addressed unit to an operating unit, said intermediate units being geometrically arranged such that they are-openly photonically connected with each other, said operating unit and said non-operating, non-addressed unit; said voltage signal having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units and being applied for sufficient time to fire or discharge said intermediate units to propagate by photonic connection the gaseous medium conditioning from said operating unit across said connecting intermediate units to said non-operating, non-addressed unit to photonically generate free electrons in said gaseous medium at said non-operating, non-addressed unit.

5. The invention of claim 4, wherein the preaddressing voltage is simultaneously applied to all of the discharge units of the panel.

6. The invention of claim 4 wherein the preaddressing voltage is of a square or rectangular waveform.

7. In a process for operating a gaseous discharge display/memory device, said device being characterized by an ionizable gaseous medium between a pair of opposed dielectric charge storage members which are respectively backed by a plurality of electrode members, the electrode members behind each dielectric member being transversely oriented relative to the electrode members behind the opposing dielectric member so as to define a plurality of discrete discharge volumes in open photonic communication, each of which constitutes a discharge unit, an alternating current sustaining voltage being maintained on all of said units, the improvement which comprises applying a voltage to at least one pilot unit sufficient to cause it to be fired or discharged; then conditioning the gaseous medium of at least one non-operating, to-be-addressed unit spaced from said pilot unit by applying between alternate halfcycles of said sustaining voltage a pre-addressing firing voltage signal to one or more intermediate units be tween said non-operating, to-be addressed unit and said pilot unit; said intermediate units being geometrically arranged such that they are openly photonically connected with each other, said pilot unit and said nonoperating, to-be-addressed unit; said voltage being applied for sufficient time to fire or discharge said one or more intermediate units to propagate, by photonic connection, conditioning of the gaseous medium from said pilot unit across said intermediate units to said nonoperating, to-be-addressed unit to photonically generate free electrons in said gaseous medium at said nonoperating, to-be-addressed unit; said voltage signal having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units; and then applying a turn-on signal to said non-operating, to-be-addressed unit.

8. The invention of claim 7 wherein the preaddresing voltage is simultaneously applied to all of the discharge units of the device.

9. The invention of claim 7 wherein the preaddressing voltages are of a square or rectangular waveform. 

1. In a gaseous discharge display/memory device characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric charge storage members which are respectively backed by a series of electrode members, the electrode members behind each dielectric member being transversely oriented relative to the electrode members behind the opposing dielectric member so as to define a plurality of discrete discharge volumes in open photonic communication, each of which constitutes a discharge unit, and wherein an alternating current sustaining voltage is maintained on all of said units and at least one discharge unit is in the ON state so as to serve as a pilot unit for the gaseous medium conditioning of other units to be addressed, the improvement wherein a pre-addressing voltage signal is applied between alternate half-cycles of said sustaining voltage to a series of intermediate units which connect at least one pilot unit to at least one unit to be addressed, said intermediate units being geometrically arranged such that they are photonically connected, said pre-addressing voltage signal being applied for sufficient time to discharge said series of intermediate units to propagate the conditioning of the gaseous medium from the pilot unit through the intermediate units to each unit to be addressed and having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units.
 2. The invention of claim 1 wherein the pre-addressing voltage is simultaneously applied to all of the discharge units of the panel.
 3. The invention of claim 1 wherein the pre-addressing voltage is of a square or rectangular waveform.
 4. In a process for operating a gaseous discharge display/memory device, said device being characterized by an ionizable gaseous medium with a multiplicity of voltage addressable gaseous discharge units in open photonic communication, an alternating current sustaining voltage being maintained on all of said units, the improvement which comprises conditioning the gaseous medium of at least one non-operating, non-addressed unit by applying between alternate half-cycles of said sustaining voltage a pre-addressing firing voltage signal to one or more intermediate units connecting the non-operating, non-addressed unit to an operating unit, said intermediate units being geometrically arranged such that they are openly photonically connected with each other, said operating unit and said non-operating, non-addressed unit; said voltage signal having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units and being applied for sufficient time to fire or discharge said intermediate units to propagate by photonic connection the gaseous medium conditioning from said operating unit across said connecting intermediate units to said non-operating, non-addressed unit to photonically generate free electrons in said gaseous medium at said non-operating, non-addressed unit.
 5. The invention of claim 4, wherein the pre-addressing voltage is simultaneously applied to all of the discharge units of the panel.
 6. The invention of claim 4 wherein the pre-addressing voltage is of a square or rectangular waveform.
 7. In a process for operating a gaseous discharge display/memory device, said device being characterized by an ionizable gaseous medium between a pair of opposed dielectric charge storage members which are respectively backed by a plurality of electrode members, the electrode members behind each dielectric member being transversely oriented relative to the electrode members behind the opposing dielectric member so as to define a plurality of discrete discharge volumes in open photonic communication, each of which constitutes a discharge unit, an alternating current sustaining voltage being maintained on all of said units, the improvement which comprises applying a voltage to at least one pilot unit sufficient to cause it to be fired or discharged; then conditioning the gaseous medium of at least one non-operating, to-be-addressed unit spaced from said pilot unit by applying between alternate half-cycles of said sustaining voltage a pre-addressing firing voltage signal to one or more intermediate units between said non-operating, to-be-addressed unit and said pilot unIt; said intermediate units being geometrically arranged such that they are openly photonically connected with each other, said pilot unit and said non-operating, to-be-addressed unit; said voltage being applied for sufficient time to fire or discharge said one or more intermediate units to propagate, by photonic connection, conditioning of the gaseous medium from said pilot unit across said intermediate units to said non-operating, to-be-addressed unit to photonically generate free electrons in said gaseous medium at said non-operating, to-be-addressed unit; said voltage signal having a polarity the same as the preceding sustaining voltage half-cycle applied to said intermediate units; and then applying a turn-on signal to said non-operating, to-be-addressed unit.
 8. The invention of claim 7 wherein the pre-addressing voltage is simultaneously applied to all of the discharge units of the device.
 9. The invention of claim 7 wherein the preaddressing voltages are of a square or rectangular waveform. 